Improvements in or relating to feed devices for internal combustion engines

ABSTRACT

The invention relates to fuel feed devices for internal combustion engines, of the kind comprising at least one fuel valve openable by an electromagnet for as long as the same is energized under the control of a signal delivered by an energizing system brought into operation simultaneously with the engine ignition system and adapted to transmit, in synchronism with the rotation of a rotating member drivable after the bringing into action of the engine ignition system, signals whose duration depends upon engine operating conditions. The energizing system comprises means which interrupt transmission of the signal and close the valve when the duration of the signal reaches a predetermined maximum value.

United States Patent Mennesson [451 Apr. 11, 197 2 541 IMPROVEMENTS IN OR RELATING TO 2,936,744 5/1960 Paule et a1 ..123/32 EA FEED DEVICES FOR INTERNAL 1 132% a g r r 40-3 3, 9 est roo et ....l EA COMBUSTION ENGINES 3,429,302 2/1969 Scholl ..123/1 19 [72] Inventor: Andre Louis Mennesson, Neuilly-sur- Seine, France FOREIGN PATENTS OR APPLICATIONS 73 Assi Sociee Industrielle De Brevets Et DEtudes 1,199,025 12/1959 France ..123/32 EA 1 g SHE Neumygupseinei France 1,206,539 2/1960 France..... 123/32 EA [221 Filed: Oct. 14, 1969 Primary Examiner-Mark M. Newman Assistant Examiner-Cort Flint [2]] 866219 Att0rneyFleit,Gipple&Jacobson [30] Foreign Application Priority Data ABSTRACT Oct. 23, 1968 France 171()95 The invention relates to fuel feed devices for internal com- Mar. 12, 1969 France ..6907041 bustion g of the kind comprising at 199M999 fuel valve openable by an electromagnet for as long as the same is ener- 52 us. c1. ..123/32 EA, 123/119 sized under the control of a Signal delivered y an energizing 511 1m. 01 ..F02d 5/00 System brought into Operation simultaneously with the engine 581 Field of Search ..123/32 12 32 EA 119 179 L ignition System and adapted to transmit, in syhchrohism with {23/179 14,03 the rotation of a rotating member drivable after the bringing into action of the engine ignition system, signals whose dura- [56] References Cited tion depends upon engine operating conditions. The energizing system comprises means which interrupt transmission of UNITED STATES PATENTS the signal and close the valve when the duration of the signal reaches a predetermined maximum value. 2,867,200 1/1959 Gryder et al ..123/32 EA 2,886,015 5/1959 Steinke ..123/32 EA 6 Claims, 2 Drawing Figures l T l i l l I r J l 9 g 6 l ,5 l

PATENTEDAPR 1 1 I972 SHEET 1 BF 2 I mvemok f/lfl/ ATTORNEYS ANDRE, LOUIS MENNESSON PATENTEDAPR 1 1 I972 SHEET 2 OF 2 I INVENTOR ANDRE LOUIS MENNESSON ATTORNEYS IMPROVEMENTS IN OR RELATING TO FEED DEVICES FOR INTERNAL COMBUSTION ENGINES The invention relates to fuel feed devices for internal combustion engines, of the kind comprising at least one fuel valve openable by an electromagnet for as long as the same is energized under the control of a signal delivered by an energizing system brought into operation simultaneously with the engine ignition system and adapted to transmit, in synchronism with the rotation of a rotating member drivable after the bringing into action of the engine ignition system, signals whose duration depends upon engine operating conditions.

The invention relates more particularly, as being the case where the invention seems likely to be most useful, but not exclusively amongst such devices to those coming under U.S. Pat. No. 3,543,739 wherein a signal is produced whenever the rotating member is in an angular position somewhere between two predetermined limits, at least one limit being variable. More particularly, the rotating member can take up a stop position such that, when the ignition contact is made without the rotating member being rotated, the energizing system delivers a signal of a duration equal to the time for which the ignition contact stays closed without the rotating member rotating. Consequently, the valve opens for a long period of time and fuel is delivered to the engine inlet pipe when the engine is stopped. This is a disadvantage of devices of this kind.

It is a main aim of the invention to improve the practical performance of such devices and inter alia to obviate the disadvantage just mentioned.

According to the invention, the energizing system comprises timing means adapted to interrupt transmission of a signal by the energizing system, and thus to close the valve, when the duration of such signal reaches a predetermined maximum value.

Preferably, the timing means comprise a capacitor adapted to be charged during the duration of each signal and, when its charge exceeds a value corresponding to the predetermined maximum duration, to interrupt the transmission of a signal to the energisation control means of the electromagnet by a transistor or any other equivalent element, the energizing system also comprising a capacitor-discharging circuit whose closure is triggered after each signal by a switch in the capacitor-discharge circuit and initiates discharge of the capacitor.

In a first embodiment of the fuel feed device wherein the switch is adapted to be controlled by a control signal, the device is so devised that each overvoltage produced in the electromagnet by suppression of its energisation forms a control signal causing the switch to close the capacitor-discharging circuit.

In a second embodiment of the fuel feed device wherein the switch is adapted to be controlled by a control signal, the device comprises an auxiliary circuit adapted to transmit during each revolution of the rotating member a control signal which is consecutive to, and of substantially the same duration as, the signal transmitted by the energizing system and which so acts on the switch that the same closes the capacitordischarging circuit for the duration of the last-mentioned control signal.

In the case in which the fuel feed device comprises at least two fuel valves controlled respectively by consecutive output signals from at least two similar energizing systems during each revolution of a single rotating member, the auxiliary circuit of either of the energizing systems is embodied by the other energizing system and vice versa, and any output signal from either energizing system to control the corresponding electromagnet is also the control signal for the switch for closing the capacitor-discharging circuit of the other energising system.

The invention can in any case be readily understood from the remainder of the description given below and from the accompanying drawings; such remainder and such drawings relate to two illustrative embodiments of a fuel feed device according to the invention.

In the drawings:

FIG. 1 is a diagrammatic view of a first embodiment of a fuel feed device according to the invention, and

FIG. 2 is a diagrammatic view of a second embodiment of a fuel feed device according to the invention.

The device shown in FIG. 1 comprises as a whole an injection valve 1 (or injector) operated by an electromagnet 2 and enabling, when open, pressurized liquid fuel to be injected into the intake pipe (not shown) of an internal combustion engine (not shown). A DC supply 3 is connected, with the interposition of a switch or ignition contact" 4, across electromagnet 2.

Energizing system B, for electromagnet 2 comprises a rotating member in the form of a flat disk 5 pierced with an appropriately shaped aperture 6 and rotated by a driving motor (not shown) around a spindle 7 perpendicular to the plane of the disk 5. The driving motor can be either the internal com bustion engine, whose starter control is assumed not to be associated with the ignition contact 4, or any kind of motor, inter alia an electric motor, whose control for starting is assumed not to be associated with ignition contact 4. System E also comprises a light source, e.g., an electric bulb 8, connected to a stabilized supply 9, and a photoelectric cell 10 on which a light beam emitted by bulb 8 and extending substantially parallel to spindle 7 is directed. Disk 5 is so placed between bulb 8 and cell 10 as to be able, as it rotates, either to interrupt the light beam going towards the cell 10 or to let the beam through aperture 6. The system formed by bulb 8 and cell 10 is movable relatively to spindle 7, and the movements of the latter system are controlled by means (not shown) responsive to the rate of intake air flow into the internal combustion engine, so that the period during which cell 10 is illuminated varies in the same sense as such air flow rate. Terminals 11, 12 are connected to terminals 13, 14 respectively of the input of an amplifying stage 15 which also forms part of system 15,. Terminal 12 is also connected to the positive terminal of supply 3 by a resistance 12a. A signal is or is not present at terminal 12 of cell 10 according as the same is or is not illuminated, and if a connection exists between terminal 12 and terminal 14, stage 15 can amplify the signals delivered by cell 10.

Stage 15 comprises two NPN-transistors l8, 19 in a Darlington circuit arrangement. Terminal 13 of stage 15 is connected to the positive terminal of supply 3 via switch 4, and terminal 14 is connected directly to base 21 of transistor 18. Collector 22 thereof and collector 23 of transistor 19 are connected to the positive terminal of supply 3 via respective resistances 24, 25 which are connected to the positive terminal of supply 3 via switch 4. Emitter 26 of transistor 18 is connected directly to base 27 of transistor 19.

Electromagnet 2 is connected to an energizing circuit 50 comprising supply 3 and switch 4, the two latter integers being connected in series with electromagnet 2 via a power transistor 20 whose collector 31 and emitter 32 are connected to terminals 16, 17 respectively of circuit 50 and whose base 30 is connected to emitter 28 of transistor 19 via resistance 29.

An injection device of this kind operates of course as follows:

It will be assumed hereinafter for the sake of explanation that the internal combustion engine (not shown) drives disk 5. When switch 4 is in the closed state-i.e., the ignition contact is madeand the engine rotates, disk 5 rotates and periodically cuts off the light beam from bulb 8. Cell 10 receives pulses of light whose duration can be adjusted in dependence upon the rate of air intake flow into the engine by a device such as that disclosed in U.S. Pat. No. 3,543,739.

When cell 10 is illuminated, its resistance becomes small and a signal appears at terminal 12. Such signal, which is assumed to be transmitted to terminal 14, is amplified by stage 15 which therefore delivers a signal to emitter 28 of transistor 19. The last-mentioned signal, which is prepared in this way by system E goes to base 30 of transistor 20 to open, i.e., to render conductive, the same, so that a large current can flow in circuit 50 and open the valve 1 controlling fuel injection into the intake pipe.

When cell 10 ceases to be illuminated, its resistance becomes high and terminal 12, and therefore base 21 has a lower potential than emitter 26. Transistors l8, 19 close or cut off, i.e., become nonconductive, and system E ceases to deliver a signal to base 30 of transistor 20, so that the same closes and produces a high electrical resistance between terminals l6 and 17. A very small current flows in circuit 50, electromagnet 2 becomes unenergised, and resilient restoring or return means (not shown) close valve 1.

To stop the engine, the ignition contact 4 is opened. Electromagnet 2 has its energization cut off and valve 1 closes and thus interrupts engine fuel supply, so that the engine stops. Disk 5 may stop in any position, inter alia in a position in which, if switch 4 were to be re-closed, the light beam from bulb 8 would pass through window 6 and be incident upon cell 10.

If the ignition contact 4 is now re-closed but the internal combustion engine starting control is not operated, the energization of electromagnet 2 by supply 3 is restored and, since cell 10 is illuminated, a continuous signal for opening transistor is emitted. Electromagnet 2 raises up and opens valve 1 so that injection occurs. Injection continues for as long as cell 10 stays illuminatedi.e., for as long as disk 5 and the engine do not rotate. This is the disadvantage previously referred to of systems of this kind.

According to the invention, to obviate this disadvantage the energizing system E comprises timing means 33 adapted to interrupt the output of a signal by the energizing system E and thus to close the valve 1, when the duration of such signal reaches a predetermined maximum value.

Advantageously, the timing means comprise a capacitor 38 adapted to be charged during the duration of the signal and, when its charge exceeds a value corresponding to the predetermined maximum duration, to interrupt the transmission by an NPN-transistor 34 (or by any other equivalent element) of a signal to base of transistor 20.

Also, the energizing system E comprises a circuit 40 which is adapted to discharge the capacitor 38 and whose closure, triggered after each signal by a switch 41 in the circuit 40, causes capacitor 38 to discharge.

Base 35 of transistor 34 is connected to collector 36 thereof via resistance 37 and, in series therewith, capacitor 38. Emitter 39 of transistor 34 is connected to input terminal 14 of stage 15, and collector 36 is connected to terminal 12 of cell 10.

Switch 41 can be an NPN-transistor whose emitter 45 is connected to base 35 of transistor 34 via resistance 37 and whose collector 46 is connected to terminal 12 of cell 10 via resistance 47.

In the embodiment shown in FIG. 1, the supply facility is so devised that each overvoltage produced in the electromagnet 2 by suppression of its energisation forms a control signal causing the switch 41 to close the capacitor-discharging circuit 40. Accordingly, base 42 of transistor 41 is connected to terminal 16 of energising circuit 50 via a serially connected resistance 43 and a voltage-regulating diode or Zener diode 44.

The fuel feed system shown in FIG. 1 therefore operates as follows:

It will first be assumed that the engine is stationary, switch 4 is open, and disk 5 is in a position such as not to interrupt the beam from bulb 8.

When switch 4 is closed but the engine starting control is not operated, electromagnet 2 is energized but disk 5 remains stationary. Cell 10 is receiving light and emitting a signal at terminal 12. Since capacitor 38 is uncharged, a current can flow from base 35 to emitter 39. Transistor 34 is relatively conductive and sufficient current can flow in base 21 of transistor 18 to render the same conductive. Transistor 20 is conductive and valve 1 opens immediately.

However, as capacitor 38 charges up at a rate dependent formed by the resistance 37 and the capacitor 38, the current in base 35 decreases so that the conductivity between collector 36 and emitter 39 of transistor 34 decreases continuously with the result that transmission thereby to stage 15 of the signal from cell 10 decreases continuously. The resulting drop in the current through base 21 produces a drop in the current flowing through electromagnet 2. When the latter current becomes too low for valve 1 to stay open, the same is closed by resilient return means (not shown).

Consequently, when the ignition contact is made but the disk 5 remains stationary, and assuming that cell 10 is illuminated in the stopped position, valve 1 stays open for only a relatively short time T which depends upon the values of resistance 37 and capacitor 38, and there is no prolonged injection of fuel. Of course, if cell 10 is not illuminated when in the stopped position, valve 1 does not open when the ignition contact is closed and when, in this case, the disk 5 remains stationary.

The timing means 33 would, however, impair normal engine operation, for unless the circuit 40 for discharging capacitor 38 operated after each signal delivered by energizing system E capacitor 38 would gradually be charged up by each such signal.

A description will now be given in greater detail of the operation of the circuit 40 in the case of normal operation of the internal combustion engine i.e., when the disk 5 is rotating. Cell 10 receives light pulses whose length or duration T varies inter alia in accordance with engine speed, but whose maximum value T is less than the predetermined timing duration of period T,.

Valve 1 opens during the time T for which cell 10 is illuminated. When disk 5 interrupts the beam incident on cell 10, the same changes over abruptly from the conductive state to the resistive state, and so the electrical resistance between terminal l6 and terminal 17 increases abruptly and the current flowing through electromagnet 2 tends to decrease abruptly. Electromagnet 2 has an appreciable inductance, and the abrupt change in the current flowing through its winding produces a considerable back e.m.f. (overvoltage) across the electromagnet 2 which may be as much as three or four times the normal voltage of the supply 3 which is, e.g., a l2-volt supply.

If a Zenerdiode 44 is used whose Zener voltage is somewhere between the normal supply voltage, e.g., 12 volts, and the back e.m.f. occurring when disk 5 interrupts the light beam, circuit 40 operates only when the back e.m.f. which can overcome the potential barrier of the Zener diode 44 is produced; the Zener voltage thereof is in the region, e.g., of 15 or 16 volts, and so the back e.m.f. previously referred to opensi.e., renders conductivethe Zener diode 44.

Base 42 of transistor 41 then becomes positive relatively to emitter 45, transistor 41 opens, capacitor 38 discharges via resistance 47 and the system is ready to operate again at the next light pulse.

When the disk 5 is stationary and the cell 10 is illuminated, the charging-up of capacitor 38 gradually closes the transistor 34 as well as the transistors 18-20, and the current flowing through electromagnet 2 gradually decreases. The resulting back e.m.f. is relatively low and below the Zener voltage of diode 44, and while the disc 5 remains stationary the valve 1 stays closed. However, when disk 5 rotates, the abrupt current decrease resulting from the disc 5 interrupting the light beam produces a high back e.m.f. which triggers diode 44 and operates switch 41 so that capacitor 38 discharges.

In some cases when the internal combustion engine is being rotated very slowly by its starter (a state not corresponding to normal engine operation as previously referred to), the time T for which cell 10 is illuminated may during starting exceed the value T The timing means 33 then provide the advantage of limiting the richness of the injected mixture by limiting the injection time on starting to the time T The means 33 can therefore help to prevent the mixture from being excessively upon the time constant of the resistance-capacity network rich which would make cold starting impossible.

Referring now to the system shown in FIG. 2, a number of elements are identical to elements in FIG. 1 and have like references. More particularly, the system shown in FIG. 2 comprises an energizing system E, for electromagnet 2 of an injection valve 1; except for the control of switch 41 by discharging circuit 40, system E, is identical to the system E, of FIG. 1.

For control of switch 41, the system of FIG. 2 comprises an auxiliary circuit 51 adapted to transmit during each revolution of the rotating member or disk 5 a control signal which is consecutive to, and of substantially the same duration as, the signal transmitted by the energising system E, and which so acts on the switch 41 that the same closes the capacitordischarging circuit 40 for the duration of the last-mentioned control signal.

The capacitor 38 therefore discharges for a time substantially equal to the time during which it was charged, thus reducing the chance of a large residual voltage build-up in capacitor 38 such as might occur during normal operation of the internal combustion engine if the discharge time of capacitor 38 were less than its charge times.

In a fuel feed system comprising two valves 1, 52 whose openings are controlled by consecutive output signals at each revolution of the rotating member 5 by two similar energizing systems [5,, E respectively, the auxiliary circuit 51 of the system E, is embodied by the other energizing system E and the auxiliary circuit 53 of the energising system E is embodied by the other energising system E,, and any output signal from either energizing system is the control signal for the switch for closing the capacitor-discharging circuit of the other energizing system.

Valve 52 is operated by an electromagnet 54 and when open allows pressurised liquid fuel to be injected into the intake pipe (not shown) into which valve 1 also permits fuel injection. Electromagnet 54 is connected to an energizing circuit 55, in the form of the power supply 3 and a switch or ignition contact 56 which is paired with the contact 4, which are connected in series with electromagnet 54 by way of a power transistor 57 whose collector 58 and emitter 59 are connected to terminals 60, 61 respectively of circuit 55.

When transistor 57 is opened by an output signal from system 15 and applied to base 62 of transistor 57, electromagnet 54 picks up and liquid fuel is injected into the intake pipe. In the absence of any signal on base 62, transistor 57 is in the closed state and valve 52 inhibits fuel injection.

The energizing system E is embodied similarly to the system E, and comprises a light source, e.g., a bulb 63, energized by a stabilized power supply 64, and a photoelectric cell 65 receiving a light beam from the bulb 63, the beam extending substantially parallel to spindle 7 of the rotating member 5 common to the two energizing systems E,, E Disk 5 is so disposed between bulb 63 and cell 65 as to be able as it rotates, either to cut off the light beam going towards cell 65 or to pass such beam through its aperture 6. The system formed by cell 65 and bulb 63 is movable relatively to spindle 7 in dependence upon the rate of air intake flow into the internal combustion engine and is at some distance from the system formed by the cell and bulb 8 to insure that the cells 10, 65 are illuminated seriatim; for instance, the two systems can be disposed symmetrically of spindle 7 in the manner shown in FIG. 2.

One output terminal 66 of cell 65 is connected directly to input terminal 68 of an amplifier stage 70 similar to stage the other output terminal 67 of cell 65 is connected to input terminal 69 of stage 70 via timing means 71 similar to the timing means 33 and comprising more particularly a capacitor 72; the same has the same function as the capacitor 38 and has connected across its terminals 73, 74 a discharging circuit 75 comprising an NPN-transistor 76 whose emitter 77 is connected to terminal 74 and whose collector 78 is connected to terminal 73 via a resistance 79.

Stage 70 of system E is similar to stage 15 of system E, and comprises more particularly an NPN-transistor 80 whose emitter 81 is connected to base 62 of transistor 57 via a resistance 82.

Accordingly, emitter 81 of transistor 80, where the signals prepared by the system B, to control the valve 52 appear, is connected, via resistance 84, to the base 83 of transistor 41 associated with capacitor-discharging circuit 40. Similarly, emitter 28 of transistor 19, where the output signals from system E, to control valve 1 appear, is connected via a resistance 86 to base 85 of transistor 76 associated with capacitor-discharging circuit 75.

This fuel feed system operates as follows:

It will be assumed that the internal combustion engine is running normallyi.e., that disk 5 is rotating. Cells 10, 65 receive consecutive light pulses whose durations T vary in accordance with the operating conditions of the internal combustion engine. It will also be assumed that the timing means 33, 71 stop transmission of signals from cells 10, 65 when such signals are longer than the time T,.

During the time T, assumed to be shorter than T, when cell 10 is illuminated, system E, supplies to emitter 28 of transistor 19 a signal causing valve 1 to open. During this time T, capacitor 38 is partially charged through resistance 37. As disk 5 continues to rotate, cell 65 is in turn illuminated for a time equal to T, if engine operating conditions have remained the same; the time interval is very close to T even if operating conditions have changed. During this time interval T the system E, applies to emitter 81 of transistor a signal for opening valve 52. Also, the last-mentioned signal opens transistor 41 for the time T, and so capacitor 38 can discharge via resistance 47 for a time equal to its charging time.

Similarly, capacitor 72, which was charged up partially during the signal from the cell 65, discharges at the next pulse which the system E, supplies and which is responsible for closing the capacitor-discharging circuit 75. The cycle just described continues while the internal combustion engine continues to rotate.

When disk 5 is stationary but cell 10 (or 65) is illuminated, the timing means 33 (or 71) act normally and interrupt transmission of signals when the duration thereof becomes T,. Similar considerations apply when the disk 5 is rotating so slowly that the signals output by the cells 10, 65 are longer than T,.

The invention therefore provides a feed system which satisfactorily meets the requirements suggested.

Iclaim:

1. In a fuel feed device for use in an internal combustion engine, which device comprises at least one fuel valve openable by an electromagnet for as long as the same is energized under the control of a signal delivered by an energizing system adapted to be brought into operation simultaneously with the engine ignition system and adapted to transmit, in synchronism with the rotation of a rotating member drivable after the bringing into action of the engine ignition system, signals whose duration depends upon engine operating conditions, a signal being produced whenever the rotating member is in an angular position somewhere between two predetermined limits, at least one limit being variable, the rotating member being arranged to control both the timing and the duration of the signal, the improvement that the energizing system comprises timing means adapted to interrupt transmission of a signal by the energizing system and thus to close the valve when the duration of such signal reaches a predetermined maximum valve which is independent of said engine operating conditions.

2. The improvement specified in claim I, wherein the timing means comprise a capacitor adapted to be charged during the duration of each signal and, when its charge exceeds a value corresponding to the predetermined maximum duration, to interrupt the transmission of a signal to the energization control means of the electromagnet by a switch element having a resistance arranged so as to depend upon the charge on the capacitor, the energizing system also comprising a capacitordischarging circuit, a switch element being arranged in the capacitor-discharge circuit so as to trigger the closure of the capacitor-discharging circuit after each signal and initiate discharge of the capacitor.

3. The improvement specified in claim 2, wherein the switch element is controlled by a control signal, and wherein each overvoltage produced in the electromagnet by suppression of its energization forms a control signal causing the switch element to close the capacitor-discharging circuit.

4. The improvement specified in claim 3 comprising a voltage-regulating diode whose threshold is less than the overvoltage and which is adapted to transmit the same to the switch element.

5. The improvement specified in claim 2, including control signal means adapted to control said switch element and an auxiliary circuit adapted to transmit during each revolution of the rotating member a control signal which is consecutive to,

and of substantially the same duration as, the signal transmitted by the energizing system and which so acts on the switch element that the same closes the capacitor-discharging circuit for the duration of the last-mentioned control signal.

6. The improvement specified in claim 5 comprising at least two fuel valves controlled respectively by consecutive output signals from at least two similar energizing systems during each revolution of a single rotating member, wherein the auxiliary circuit of either of the energizing systems is embodied by the other energizing system and vice versa, and any output signal from either energizing system to control the corresponding electromagnet is also the control signal for a switch element for closing the capacitor-discharging circuit of the otherenergizing system. 

1. In a fuel feed device for use in an internal combustion engine, which device comprises at least one fuel valve openable by an electromagnet for as long as the same is energized under the control of a signal delivered by an energizing system adapted to be brought into operation simultaneously with the engine ignition system and adapted to transmit, in synchronism with the rotation of a rotating member drivable after the bringing into action of the engine ignition system, signals whose duration depends upon engine operating conditions, a signal being produced whenever the rotating member is in an angular position somewhere between two predetermined limits, at least one limit being variable, the rotating member being arranged to control both the timing and the duration of the signal, the improvement that the energizing system comprises timing means adapted to interrupt transmission of a signal by the energizing system and thus to close the valve when the duration of such signal reaches a predetermined maximum valve which is independent of said engine operating conditions.
 2. The improvement specified in claim 1, wherein the timing means comprise a capacitor adapted to be charged during the duration of each signal and, when its charge exceeds a value corresponding to the predetermined maximum duration, to interrupt the transmission of a signal to the energization control means of the electromagnet by a switch element having a resistance arranged so as to depend upon the charge on the capacitor, the energizing system also comprising a capacitor-discharging circuit, a switch element being arranged in the capacitor-discharge circuit so as to trigger the closure of the capacitor-discharging circuit after each signal and initiate discharge of the capacitor.
 3. The improvement specified in claim 2, wherein the switch element is controlled by a control signal, and wherein each overvoltage produced in the electromagnet by suppression of its energization forms a control signal causing the switch element to close the capacitor-discharging circuit.
 4. The improvement specified in claim 3 comprising a voltage-regulating diode whose threshold is less than the overvoltage and which is adapted to transmit the same to the switch element.
 5. The improvement specified in claim 2, including control signal means adapted to control said switch element and an auxiliary circuit adapted to transmit during each revolution of the rotating member a control signal which is consecutive to, and of substantially the same duration as, the signal transmitted by the energizing system and which so acts on the switch element that the same closes the capacitor-discharging circuit for the duration of the last-mentioned control signal.
 6. The improvement specified in claim 5 comprising at least two fuel valves controlled respectively by consecutive output signals from at least two sImilar energizing systems during each revolution of a single rotating member, wherein the auxiliary circuit of either of the energizing systems is embodied by the other energizing system and vice versa, and any output signal from either energizing system to control the corresponding electromagnet is also the control signal for a switch element for closing the capacitor-discharging circuit of the other energizing system. 